A. Bergeat

A crossed-beam study of the reaction C(1D)+H2(X1Σ+, v=0)→CH(X2Π, v′)+H(2S)

Abstract Product angular and time-of-flight distributions have been measured for the first time for the prototypical insertion reaction C( 1 D)+H2 using the crossed-beam technique with mass spectrometric detection at the collision energy of 1.86 kcal mol−1. Center-of-mass angular and kinetic energy distributions have been derived for CH(X 2 Π , v′=0)+H products and compared with those of statistical calculations based on phase-space theory.

Dynamics of the insertion reaction C(1D) + H2: A comparison of crossed molecular beam experiments with quasiclassical trajectory and quantum mechanical scattering calculations

In this paper we report a combined experimental and theoretical study on the dynamics of the prototype insertion reaction C(1D) + H2. Product angular and velocity distributions have been obtained in crossed beam experiments at two collision energies of 7.8 and 16.0 kJ mol−1. Quasiclassical trajectory (QCT) and quantum mechanical (QM) scattering calculations have been carried out on a recent accurate ab initio potential energy surface at the energies of the experiments. The molecular beam results have been simulated using the theoretical calculations. Reasonably good agreement between experiment and theory is found.

A low temperature investigation of the N(4S degrees) + NO reaction.

The kinetics of the N((4)S degrees) + NO(X(2)Pi) reaction have been studied in a continuous supersonic flow reactor over the range 48 K <or= T <or= 211 K. Nitrogen atoms were produced by microwave discharge upstream of the Laval nozzle and were probed in the vacuum ultraviolet by resonance fluorescence. The reaction has been found to exhibit a small negative temperature dependence, with a rate coefficient decreasing from (5.8 +/- 0.3) x 10(-11) cm(3) molecule(-1) s(-1) at 48 K to (3.3 +/- 0.2) x 10(-11) cm(3) molecule(-1) s(-1) at 211 K with the statistical uncertainties cited at the level of a single standard deviation from the mean.

Dynamics of the C+C2H2 reaction from differential and integral cross-section measurements in crossed-beam experiments

The reaction between atomic carbon and acetylene has been investigated using complementary crossed molecular beam techniques. Differential cross sections have been obtained for the reactions of both ground and excited carbon atoms, C(3PJ, 1D2)+C2H2(X 1Σg+), in experiments conducted with continuous supersonic beams, mass spectrometric detection, and time-of-flight analysis at a relative translational energy of 29.3 kJ mol−1. The reaction C(3PJ)+C2H2(X 1Σg+) has been found to lead to C3H+H and C3+H2 products in comparable amounts. Both H and H2 elimination pathways are found to proceed through the formation of a C3H2 long-lived intermediate complex whose lifetime may be comparable to its rotational period. The spin-forbidden H2 elimination channel is attributed to the occurrence of intersystem-crossing between the triplet and singlet manifolds of the C3H2 potential-energy surfaces. The reaction C(1D2)+C2H2(X 1Σg+) has been found to lead to formation of C3H+H, with a C3H center-of-mass angular distribution s...

Relevance of the Channel Leading to Formaldehyde + Triplet Ethylidene in the O(3P) + Propene Reaction under Combustion Conditions

Comprehension of the detailed mechanism of O((3)P) + unsaturated hydrocarbon reactions is complicated by the existence of many possible channels and intersystem crossing (ISC) between triplet and singlet potential energy surfaces (PESs). We report synergic experimental/theoretical studies of the O((3)P) + propene reaction by combining crossed molecular beams experiments using mass spectrometric detection at 9.3 kcal/mol collision energy (Ec) with high-level ab initio electronic structure calculations of the triplet PES and RRKM/master equation computations of branching ratios (BRs) including ISC. At high Ecs and temperatures higher than 1000 K, main products are found to be formaldehyde (H2CO) and triplet ethylidene ((3)CH3CH) formed in a reaction channel that has never been identified or considered significant in previous kinetics studies at 300 K and that, as such, is not included in combustion kinetics models. Global and channel-specific rate constants were computed and are reported as a function of temperature and pressure. This study shows that BRs of multichannel reactions useful for combustion modeling cannot be extrapolated from room-temperature kinetics studies.